Method of arresting arsenic fumes.



No.. 746,251. PATBNTED DEG. 8,1903.

R. BAGGALEY.

METHOD 0F ARRBsTIN-G ARSENIC FUMBS.

APPLIOATION FILED APB.. 23. 1903.

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R. BAGGALEY. METHOD 0F ARRESTING ARSENIC PUMBs.

APPLICATION FILED APR. 23.' 1903.

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UNITED STATES Patented December 8, 1903.

PATENT OFFICE.

METHOD OF ARRESTING ARSENIC FUMES.l

SPECIFICATIN'formin'g part of llllettersV Patent No.1746,251, dated December 8, i903. Application filed April 23.' 1903. Serial No. 153.942. tNo specimens.) l

To a/ZZ whom itlntcty concern:

Pittsburg, Allegheny county, Pennsylvania, have invented a new and useful Method of Arresting Arsenic Fumes, of which the fol'- lowing is a specification. g

Figure l of the accompanying drawingsis aside elevation of apparatus for carrying out Fig. 2 isl a vertical section of the upper part of the apparatus on the line Il lI of Fig. l. -lig. 3 is a plan view of the apparatus, on a smaller .scale, sh'owing the same connected with alstack S for creating a draft therethrough. Fig. 4 is a vertical crosssection on the line IV 1V of Fig. 3. Fig. 5 is an end elevation, partly in section, showing the connection of the smelter-furnace 4 with the chamber of my apparatus. Fig. (i is a vertical cross-section, on a larger scale, onl

the line VI VI of Fig. 1. Fig. 7 is a partial side elevation, partly in central longitudinal section.

My invention relates to a `new method of preventing the devastating effects to vegetation and to the streams arising from the smelting of ores containing sulfur, arsenic, (lac. ltis well known that the country surroundingsmelting plantssometimes formally miles distant is devastated through the destruction of vegetation bythe fumes inseparable fromI the fusion of sultid ores.

In a furnacesmelting three hundred and sixty tons of ore that'contains, say, twenty v per cent. of sulfur from sixty to seventy-five tons of sulfur are volatilized and of course deposited in the surrounding country. On damp or rainy days the sulfur will fall Within a short distance of the smelter-stack. On clear days it will often be carried for a distance of fifteen or twenty miles. The result is the same wherever it falls. Vegetation is destroyed, and the sulfur is carried by theI surface drainage into the streams and ponds and the water is polluted'and rendered unfit for use. A still more injurious effect is proventiu an economical manner these objectionable features of the smelting industry as at present practiced, but at the same time when desired to collect as by-products sulfur and arsenic that have heretofore been wasted.

My invention isfounded on the fact that charcoal will absorb from forty to fifty times its volume of sulfur and sulfur-dioxid gases.

In thesmelting of' sulfid ores approximately one-half the sulfur contents of the orepass off in the form of free sulfur. The remaining gases contain from fourteen to fifteen per cent. of sulfur dioxid and are practically identicalwith the gases produced by roasting pyrites in the kilns employed in sulfuricacid manufacture.

I have found that by interposingcharcoa screens or filters within enlarged chambers located between the smelting-furnace and the stack or located between the smelting furnace and a suitable fan or other mechanical device for producing an induced draft these obnoxious sulfurfunnes will be absorbed `effectually up to the point where the charcoal has been increased approximately twenty per cent. of its weight. Above this point the sulfur fumes are not entirely arrested. -Therefore if it is desired in practicing my invention to remove all 0f the `sulfur from the fumes the charcoal m ust be changed whenever its Aweight has been increased by such deposit state or as sulfur-dioxid gas, will approximate sixty tons. Theoretically this'would require for purification of thegases aton and a half of charcoal daily. In my apparatus I provide successive filters, preferably three in number, each containing from two to two',

and a half tous of charcoal. These should be located far enough from the smelting-furnace to prevent ignition from the hot gases.

I have found that charcoal is subject to what is called in the trade spontaneous combustion, which I believe to be caused by the occurrence of red-hot centers protected from the atmosphere by a casing of cold non-conducting charcoal and which when exposed to air burst into flame. It is therefore of irnportance that provision be made for drenching the charcoal screens from above with water. After the charcoal in each screen has absorbed sulfur up to its limit I discharge it below into a car for removal to a suitable steam retort or tank,where the contained sulfur is melted out by means of steam nndera pressure of approximately fifty pounds to the square inch. This yields a temperature of approximately 300 Fahrenheit, and as sulfur melts at 239 Fahrenheit it is apparent that the sulfur is thus removed from the chal'- coal and the charcoal rendered capable of being used again for the same purpose. The third screen provided in myapparatusalso contains charcoal which is constantly drenched or saturated either with a dilute solution of sulfd of calcium or with a simple alkaline solution of any kind that can be cheaply and readily obtained. Such solution can be used many times and will effectually throw down and arrest the arsenic contained in the gases.

In the drawings, 2 is a chamber which, as shown in Figs. Sand 5, connected at one end with the downcomer-pipe 3 of the smel-terfurnace 4 and at the other end is connected to a fan F for producing an induced draft7 as shown in Fig. l, or with a stack S, as shown in Fig. 3.

The chamber 2 is intersected at intervals by the screens above mentioned. Each of these screens is formed by vertical double walls 5 5, made of bricks or tiles, having perforations (l, which are upwardly inclined in order to prevent loss of the charcoal contents and which offer free passage to the smeltergases. At the upper end each space or chainber between the walls 5 5 communicates with a feedingchamber 7, preferably having upwardly-converging walls and communicating with a feed-hopper 8, and at its lower end it has discharge-openings 9, preferably formed with downwardly-converging sides fitted With valves l0 and adapted to discharge into cars ll, which travel on tracks beneath the chamber. At the ends of the screen spaces or chambers are openings l2, fitted With suitable doors and adapted to permit the admission of a poking-tool when it is desired to facilitate the discharge of the contents.

At the upper end of each screen-chamber are pipes 13, by which Water or alkaline solution may be introduced in quantities as desired.

In use of the apparatus the screen-chambers between the perforated Walls are lilled Withcharcoal introd uced through the hoppers, and the charcoal of the third screen is kept drenched from the pipes 13 by a simple alkaline solution or a solution of snld of calcium for the sole purpose of precipitatingr any remaining arsenic.

In order to present fresh charcoal surfaces to the gases from time to time, a part of the charcoal is withdrawn at the bottom of the screexrchambers, its place being taken by charcoal fed through the hop pers. 'lhe charge of the charcoal is governed by the percentage of impurities contained in the ores under treatment.

I do notclaim herein the method above described for arresting sulfur fumes, since I have made it the subject of another patent application.

I claiml. The method herein described of arresting arsenic fumes from smclt-er-gases which consists in passing the gases containing such fumes through a filter containingr an alkaline compound; substantially as described.

2. The method herein described of arresting arsenic fumes from smelter-gases, which consists in passing the gases containing such fumes through a lilter charged with charcoal and wetting the charcoal with an alkaline solution; substantially as described.

3. The method herein described of arresting arsenic fumes from smelter-gases, which consists in passing the gases containing such fumes through a filter containing sulfid ot' calcium; substantially as described.

In testimony whereof I have hereunto set my hand.

RALPH BAGGALEY.

Witnesses:

GEO. B. BLEMING, JOHN MILLER. 

